Mizuno JPX 921 Hot Metal, Hot Metal Pro irons

A thinner, more-flexible face helps Mizuno’s newest game-improvement irons deliver more power without growing in size.

Gear: Mizuno JPX 921 Hot Metal, Hot Metal Pro irons
Price: $1,000 (4-GW)/$125 per club with Nippon N.S. Pro 950 NEO steel or UST Mamiya Recoil ESX graphite shafts and Golf Pride MCC +4 grips
Specs: Cast 4140 Chromoly with a cup-face design and pocket cavity.
Available: Sept. 17

It is not uncommon for golfers on the PGA Tour to compliment their irons with a game-improvement club or a distance-oriented long iron at the top of their set. Those clubs tend to create more distance, a higher launch and a quicker stop on the greens. For example, Paul Casey has played a Mizuno Hot Metal Pro 3-iron for more than a year because the club is easier to hit from long range than his Mizuno MP-5 muscleback blades.

Many amateurs need that kind of distance and height gains not only in their long and mid-irons but throughout the set, and for years they were offered oversized clubs that produced those attributes but that often were not the best looking clubs.

Now, recreational golfers who are turned off by oversized clubs but who want more distance and forgiveness can benefit from more normal sized, perimeter-weighted clubs that have flexible faces. Mizuno has two new offerings – the JPX 921 Hot Metal and JPX 921 Hot Metal Pro – made to do that.

Mizuno JPX 921 Hot Metal irons
Mizuno JPX 921 Hot Metal irons (Mizuno)

Instead of being forged from soft carbon steel, the Hot Metal irons are cast from 4140 Chromoly, a much harder material. Its strength allowed Mizuno designers to make the faces of the Hot Metal irons very thin. The center of the hitting area is thinner than the previous Hot Metal and Hot Metal Pro, and that ultra-thin area is larger than in the predecessors. With a large pocket cavity behind the hitting area, it also flexes more efficiently for increased ball speed.

To broaden the sweet spot, Mizuno gave the Hot Metal irons a cup-face design, with the edges of the face behind the seams of the leading edge, the toe and the topline. When the ball hits the face, the leading edge acts as a hinge and activates a larger area.

Mizuno JPX 921 Hot Metal Pro irons
Mizuno JPX 921 Hot Metal Pro irons (Mizuno)

Finally, extra sound ribs were positioned around the frame’s perimeter to improve the impact sound and feel.

The only difference between the Hot Metal and the Hot Metal Pro is size. The Pro version shares the same materials and construction, but it has a shorter blade length, slightly thinner topline, less offset and slightly narrower sole.